The regulation of the synthetic and degradative enzymes involved in cell wall synthesis during the cell division cycle, and the effects of highly specific beta-lactam antibiotics on wall synthesis will be studied. Various experimental conditions (conditional mutants, mecillinam-resistant mutants, and synchronous cultures) are being developed which should permit the study of cell elongation and cell septation separately. It is postulated that wall synthesis during elongation is enzymatically distinct from wall synthesis during septation. We will attempt to prove the existence of separate pathways and determine the controls that permit the cell to shift from elongation to septation during the cell division cycle. Mutants that lack the ability to bind penicillin to specific penicillin-binding proteins have been isolated recently in our laboratory and should facilitate study of elongation and septation.